CVE-2008-0535 in Service Control Engine
Summary
by MITRE
Unspecified vulnerability in the SSH server in (1) Cisco Service Control Engine (SCE) before 3.1.6, and (2) Icon Labs Iconfidant SSH before 2.3.8, allows remote attackers to cause a denial of service (device instability) via "SSH credentials that attempt to change the authentication method," aka Bug ID CSCsm14239.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability described in CVE-2008-0535 represents a critical denial of service weakness affecting SSH server implementations in specialized network infrastructure devices. This issue impacts Cisco Service Control Engine platforms running software versions prior to 3.1.6 and Icon Labs Iconfidant SSH implementations below version 2.3.8. The flaw manifests when remote attackers submit SSH credentials designed to alter the authentication mechanism, creating a condition that leads to device instability and potential system crashes. The vulnerability operates at the protocol level within SSH server implementations, specifically targeting how the system handles authentication method transitions and credential validation processes. This represents a fundamental weakness in the authentication subsystem that could be exploited without requiring elevated privileges or complex attack vectors.
The technical nature of this vulnerability stems from inadequate input validation and state management within the SSH server component. When legitimate authentication credentials are presented with intentions to modify authentication methods, the system fails to properly handle the transition sequence, leading to memory corruption or resource exhaustion conditions. The flaw operates through a classic buffer over-read or improper state handling mechanism that causes the SSH daemon to enter an unstable condition. This type of vulnerability aligns with CWE-121, which categorizes buffer overflow conditions, and CWE-248, which covers improper exception handling. The attack vector requires only network connectivity to the affected SSH service, making it particularly dangerous as it can be exploited by remote unauthenticated attackers.
From an operational impact perspective, this vulnerability creates significant risks for network infrastructure security and availability. The device instability resulting from exploitation can lead to complete service disruption, requiring manual intervention for system recovery and potentially causing extended downtime for critical network services. Organizations relying on Cisco SCE or Icon Labs Iconfidant SSH systems face potential operational disruptions that could affect billing services, traffic control, and overall network management functions. The vulnerability's exploitation can result in cascading failures within network infrastructure, as the affected devices may become unresponsive to management traffic and unable to process legitimate user requests. This represents a substantial risk to network reliability and business continuity operations.
Mitigation strategies for this vulnerability require immediate software updates and patches for all affected systems. Organizations should prioritize upgrading Cisco Service Control Engine platforms to version 3.1.6 or later and Icon Labs Iconfidant SSH implementations to version 2.3.8 or higher. Network administrators should implement additional monitoring and alerting for unusual authentication patterns that might indicate exploitation attempts. The vulnerability's classification under the ATT&CK framework would place it within the Privilege Escalation and Defense Evasion domains, as attackers could potentially use this weakness to maintain persistent access or evade detection mechanisms. Additional protective measures include implementing SSH access controls, limiting SSH service exposure through network segmentation, and establishing robust network monitoring to detect anomalous authentication behaviors that could indicate exploitation attempts.